Hyperfine field systematics of s-p impurities in Gd

A Categorical View to Structural Complexity

“…In [5] are proposed the basic questions: What does it mean to say that a problem A "approximates" an optimization problem B? What is it understood by the "best approximation" for such an optimization problem?…”

“…In this context, reductions between optimization problems are considered as morphisms in the categorial sense, being optimization and approximation problems viewed as the obvious objects. After introducing the optimization problems categories OPTS and OPT, as well as related questions in [4,5], a formal system modelling the approximation hierarchy of a given optimization problem is provided, based on categorical shape theory [3].…”

Theoretical study of hyperfine fields at impurity nuclei in GdX (X=Zn,Cd) compounds: A two-center model

“…As far as ferromagnetic Gd host is concerned, the experimental results can be compared with the calculation of Leal et al, 2 which is an extension of the Daniel-Friedel model. 3 More recently, de Oliveira et al 4 have discussed the problem of nonmagnetic impurities in Gd and Ni hosts, using a formulation due to Speier et al, 5 which takes into account neighbor effects arising from the translational symmetry breaking.…”

The hyperfine field at rare-earth impurities diluted in Fe, Co and Ni hosts: a theoretical study

“…The formation of local moments and its connection to the hyperfine interactions is one of the central problems in the description of the magnetic properties of metals [1][2][3][4][5][6][7]. In particular, many theoretical works based either on first-principles calculations or on model approaches have been devoted to the study of the systematics of the magnetic moments and the hyperfine fields at impurity sites diluted in ferromagnetic transition metals and rare-earth hosts [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Very recently, we have extended a theoretical formulation including the change in the energy of the hopping between the impurity and the nearest neighbours [23][24][25] to study the local magnetic moments and the hyperfine fields at La, Gd and Lu impurities diluted in Fe and Ni ferromagnetic hosts [22].…”